MOUNTAIN GATE, Calif. (AP) - An autistic teenager suffered a head injury and a broken elbow in a beating by three sheriff's deputies who mistook him for a prowler, authorities say.

Pierre Cowell, a 17-year-old who does not speak, had wandered from his home early Friday.

A neighbor, who did not recognize him, called 911 after seeing him outside her home about 2 a.m., Capt. Tom Bosenko said Monday. The woman became alarmed when she heard the doorknob jiggling, he said.

As three deputies approached the house, Cowell ran toward them and bumped one of them, Bosenko said. When Cowell didn't respond to the officers' commands, they used a baton, stun gun and pepper spray to subdue him.

"The officers were very much concerned for their safety," Bosenko said, adding that the deputies thought Cowell was under the influence of drugs. He said that the officers did not know that an autistic teenager was missing at the time.

Cynthia Cowell said she was unaware her son had left their home Friday until deputies came to her door.

"He doesn't understand anything to do with danger. He has to have someone constantly with him," she said.

She said she was surprised the deputies did not know he was autistic until she told them. "Being totally nonverbal would be a clue," she said.